Security films and slit micro tapes are well known to the industry. These are known as security thread also. This “thread” can be seen embedded almost in most of the currency paper. The process of manufacture and its insertion is also well known for many years. The following patents describe various types of security threads and the process of their insertion into the paper.
U.S. Pat. No. 5,002,636 describes a method of making security paper comprising the steps of providing a strip of plastic material; applying a soluble pigmented material on said plastic strip; applying a layer of metal over said soluble pigmented material; printing over said metal with an insoluble pigmented material to provide printed indicia; removing said metal and said soluble pigmented material from said plastic strip except from under said printed indicia to form a security thread; and embedding said security thread in a colored paper.
The security strip of the above patent requires a protective layer of plastic material over said security thread prior to embedding said security thread in said paper. Also, the removal of said metal and said soluble pigmented material includes steps of either ethyl alcohol etching or incase of a water soluble pigmented material will include the steps of water dissolution. Hence, the process is quite complex and consumes a lot of time
U.S. Pat. No. 4,761,205 describes a method of forming a security paper by inserting the security thread within paper fiber slurry at a predetermined location in a papermaking machine during dewatering of said fiber slurry before said fiber is consolidated into a continuous paper web. The security thread is formed either by printing indicia on the metalized plastic film by the help of a varnish resistant to metal reactive solvent and then subjecting the film to a metal reactive solvent; or hot stamping metallic indicia onto a plastic film; or by selectively metalizing metal indicia onto a continuous planar plastic film; or by transferring metal indicia from a substrate onto a continuous plastic film.
However, it has been found that these types of products can be simulated by counterfeiters, by virtue of the increased availability of technology.
U.S. Pat. No. 4,552,617 relates to thin strips of a carrier material, microprinted identifying indicia, which dissolves during the dewatering and drying stage of the paper making process. The microprinted indicia remains intact and is readable by means of transmitted light yet is neither legible nor reproducible with reflected light.
However, these films whether water soluble or plastic can only be inserted into the paper web in the form of a thread and that too in the machine direction only. It is not possible to insert these threads with different patterns and shapes into the paper web. E.g. a paper currency cannot be seen with round shaped thread inserted into it. Also, these products can be counterfeited easily due to lack of higher degree of security.
Also, security elements such as UV fibres, tracers, taggants and the like are randomly mixed in pulp as paper is formed. As much of the paper making process at the initial stage is maximum water, which is drained and recycled, these elements are lost or conglomerated at a non-discreet area, which results in monetary losses. These security/elements are very expensive.
It has been the endeavor of all security paper mills to control costs, and so if these security features can be precisely guided into a known location, for example by using the printed text of the security thread, then there can be a lot of cost saving.
Further, embedding of security thread at a precise place slows down the paper machine thus giving lesser yield of paper. Wider width security thread has it's own problem as the pulp fibres have to flow onto a wider area thus slowing down the machine further. Embedding of security thread also creates uneven bumps at certain places which necessitates the web to be moved sideways to spread the tension values throughout the cross direction of the web. This curtails higher lengths of paper to be wound on a single roll, which results in lesser yields due to various roll changes. This needs higher margin of variance for registration of the thread in the paper web.
Hence, to be ahead of the fraudsters there is a need to develop new and complex products and hence enhance the degree of security so that the product will not be simulated easily and at the same time such security thread with high degree of security is inserted into the paper web using existing paper making process so as not to incur costs of new machinery and equipments.
Hence, the main objective of the present invention is to provide multiple security features on individual indicia or graphics in the security film.
Another objective of the present invention is to eliminate the process of demetallization and thus avoid the use of corrosive solvents.
Yet another objective of the present invention is to provide a security film having indicia printed in a particular pattern and shape and inserting the security film into the paper during the paper making process so as to restrict the counterfeiters from simulating the product.